Here you can find the source of isBlank(Collection> c)
public static boolean isBlank(Collection<?> c)
//package com.java2s; //License from project: Open Source License import java.util.*; public class Main { public static boolean isBlank(Collection<?> c) { return c == null || c.isEmpty(); }/*from ww w . j a v a 2 s. c o m*/ public static boolean isBlank(Map<?, ?> m) { return m == null || m.isEmpty(); } }